JP4469345B2 - Boiling water reactor and method for suppressing acoustic vibration of steam piping in boiling water reactor - Google Patents

Description

  The present invention relates to a boiling water reactor and a method for suppressing acoustic vibration of a steam pipe in a boiling water reactor, and more particularly to a boiling water reactor and a boiling water type suitable for suppressing pressure vibration of a main steam system. The present invention relates to a method for suppressing acoustic vibration of steam piping in a nuclear reactor.

  When the power generation capacity of a boiling water reactor is increased, pressure oscillations in the steam dome and steam piping (hereinafter collectively referred to as the main steam system) increase as the steam flow rate increases, and the main steam system Cases that are thought to be the cause of damage to various devices have been reported. Therefore, measures such as optimizing the flow path shape of the main steam system and increasing the structural strength are taken in order to avoid damage to the main steam system pipes and valves and various equipment. The method is reported in Non-Patent Document 1 and the like.

  For example, Non-Patent Document 2 discloses a technique using a Helmholtz resonance tube in the field of thermal power generation in order to attenuate acoustic vibration of a gas turbine combustion chamber.

NRC SPECIAL INSPECTION REPORT, 50-265 / 03-11 Journal of Engineering for Gas Turbines and Power, April 2004, Vol.126 P.271-275

  One possible cause of pressure oscillations in the main steam system in boiling water reactors is vibrations due to acoustic resonance. In other words, in the main steam system from the steam dome of the reactor pressure vessel to the high-pressure turbine through the steam pipe, pressure waves are generated due to fluid flow rate fluctuations and propagated and reflected in the steam pipe system. . As a result, a standing wave (acoustic resonance mode) having a large amplitude is formed, and the amplitude of the pressure vibration may be amplified (that is, resonant vibration). In particular, in a power plant having an increased power generation capacity, the fluid flow rate fluctuates with an increase in the steam flow rate, which may cause a large acoustic resonance. Such an acoustic resonance phenomenon is affected by the piping configuration and boundary conditions of the power plant, and therefore has different vibration characteristics for each power plant. Therefore, it is difficult to predict in advance the frequency, amplitude, and maximum amplitude position of vibration due to acoustic resonance. Therefore, in order to ensure the soundness of the main steam system and various devices, it is necessary to design the main steam system and various devices with a sufficiently large design margin. However, increasing the design margin in this way becomes a factor that further increases the facility cost of the power plant.

  Therefore, as a method for preventing the equipment cost of the power plant from soaring, by applying the technique of Non-Patent Document 2, acoustic resonance generated in the main steam system by attaching a Helmholtz resonance pipe to the main steam system such as a steam dome or steam pipe. A method of suppressing this is conceivable. However, in the main steam system, non-condensable gas such as hydrogen gas is transported in the steam. Since such non-condensable gas is lighter than steam, it is transported through the upper part of the steam pipe. Therefore, if the Helmholtz resonance tube is attached to the upper part of the steam pipe, hydrogen gas or the like may stagnate inside the Helmholtz resonance tube, which may be unfavorable for safety. Also, if the Helmholtz resonance tube is attached to the lower part of the steam pipe, the drain generated by the steam transported through the steam pipe stagnate inside the Helmholtz resonance pipe, and the internal volume (volume) of the Helmholtz resonance pipe is increased. There is a risk that the effect of suppressing acoustic resonance will be lost.

  The present invention has been made in view of the above circumstances, and is effective for pressure vibration accompanying acoustic resonance generated in the main steam system without stagnation of noncondensable gas and drain inside the Helmholtz resonance tube. It is an object of the present invention to provide a boiling water reactor capable of suppressing the Helmholtz resonance tube in an appropriate state, and a method for suppressing acoustic vibration of steam piping in the boiling water reactor. Is.

  The boiling water reactor according to the present invention is characterized in that a Helmholtz resonance tube is attached in a substantially horizontal direction to a side portion of a main steam system from a steam dome in a reactor pressure vessel to a steam pipe. With such a configuration, the non-condensable gas such as hydrogen gas transported in the vapor is transported through the upper part of the main steam system, so that the non-condensable gas stagnates in the Helmholtz resonance tube. There is no fear. Therefore, the Helmholtz resonance tube during operation can always be maintained in an appropriate state.

  In a preferred embodiment of the boiling water reactor according to the present invention, the Helmholtz resonance tube is a continuous surface having a flat bottom surface, and the bottom surface of the main steam system has a downward slope toward the main steam system. Attached to the side. With such a configuration, the drain generated by the steam inside the Helmholtz resonance tube is continuously discharged to the main steam system, so there is no possibility that the drain stays inside the Helmholtz resonance tube. Therefore, the volume of the Helmholtz resonance tube can always be maintained at a constant value. Thus, if pressure oscillation caused by acoustic resonance generated in the main steam system is detected and the sectional area of the inlet pipe of the Helmholtz resonance pipe is controlled (that is, if the opening degree of the opening adjustment valve in the inlet pipe is controlled). ), The amplitude of the pressure vibration can be effectively suppressed to the minimum value.

  In another preferred embodiment of the boiling water reactor according to the present invention, the Helmholtz resonance pipe is installed at the upper part of the main steam system, and further, the main steam system is vented from the upper part of the Helmholtz resonance pipe through the vent pipe. You may comprise. With such a configuration, there is no possibility that drain and non-condensable gas are stagnated in the Helmholtz resonance tube. Therefore, as in the case of the above-described configuration, the safety of the Helmholtz resonance tube can be maintained during operation, and the volume of the Helmholtz resonance tube can be kept constant and the sectional area of the inlet pipe can be controlled effectively. It is possible to suppress acoustic resonance.

  According to the present invention, pressure vibration accompanying acoustic resonance generated in the main steam system can be effectively suppressed without causing non-condensable gas or drain to stagnate inside the Helmholtz resonance tube.

"Overview"
The boiling water reactor of the present invention pays attention to the main factor of pressure oscillation in the main steam system being acoustic resonance, and uses a Helmholtz resonance tube to avoid the acoustic resonance. For example, a cylindrical Helmholtz resonance pipe consisting of a cylindrical inlet pipe and a resonance damping pipe is attached to the main steam system, and the sectional area of the inlet pipe or the volume of the resonance damping pipe (hereinafter collectively referred to as the resonance pipe form factor) Is changed to change the resonance frequency of the Helmholtz resonance tube. Thus, by finely adjusting and changing the resonance tube form factor of the Helmholtz resonance tube, the resonance frequency of the Helmholtz resonance tube is matched with the frequency of the acoustic resonance generated in the main steam system. As a result, the amplitude of acoustic resonance generated in the main steam system (hereinafter referred to as acoustic vibration) is attenuated, and as a result, the pressure vibration generated in the main steam system can be reduced. Note that the shapes of the inlet pipe and the resonance damping pipe are not necessarily limited to the cylindrical shape.

  In the boiling water reactor of the present invention, a Helmholtz resonance tube is attached to a side of a main steam system such as a steam dome or a steam pipe in a substantially horizontal direction, and non-condensable gas such as hydrogen gas is stagnated inside the Helmholtz resonance tube. To prevent you from doing. That is, the non-condensable gas mixed in the vapor is transported along with the vapor through the upper part of the main vapor system, so that the non-condensable gas stagnates inside the Helmholtz resonance tube attached to the side of the main vapor system. There will be nothing.

  Furthermore, desirably, the portion of the inlet piping attached to the main steam system is downward so that the drain generated by the steam inside the Helmholtz resonance pipe that is ventilated with the main steam system does not stay inside the Helmholtz resonance pipe. Mount the Helmholtz resonance tube on the side of the main steam system so that it faces down. That is, the Helmholtz resonance tube is inclined and attached to the side of the main steam system so that the drain inside the Helmholtz resonance tube is continuously discharged to the main steam system.

  As another form of the boiling water reactor according to the present invention, a Helmholtz resonance pipe is attached above a main steam system such as a steam dome and a steam pipe, and a vent pipe is attached to an upper part of the Helmholtz resonance pipe. The piping may be returned to the system. As a result, the non-condensable gas flowing into the Helmholtz resonance tube from the upper part of the main steam system is continuously returned to the main steam system through the vent pipe, so there is no possibility that the non-condensable gas stagnates in the upper part of the Helmholtz resonance pipe. Disappear. Furthermore, since the Helmholtz resonance tube is attached to the upper part of the main vapor system, there is no possibility that drain is stagnated inside the Helmholtz resonance tube, and the internal volume (volume) of the Helmholtz resonance tube is maintained at a constant value. Therefore, acoustic resonance can be stably suppressed.

  Hereinafter, a boiling water reactor according to an embodiment of the present invention will be described in detail with reference to the drawings. First, a Helmholtz resonance tube used in a boiling water reactor of the present invention to suppress acoustic vibrations. explain.

《Helmholtz resonance tube》
FIG. 1 is a side view showing the structure of a cylindrical Helmholtz resonance tube 12 suitable for use in the boiling water reactor of the present invention. As shown in FIG. 1, the Helmholtz resonance tube 12 includes two components, a cylindrical inlet pipe 121 and a cylindrical resonance damping pipe 122. The shapes of the inlet pipe 121 and the resonance attenuation pipe 122 are not necessarily limited to the cylindrical shape. The resonance frequency f of the Helmholtz resonance tube 12 can be expressed by the following equation (1).

f = c / (2π) × (An / (V · Ln)) ^0.5 (1)
Here, f is the resonance frequency (Hz), c is the speed of sound (m / s), An is the sectional area (m ² ) of the inlet pipe 121, V is the volume (m ³ ) of the resonance damping pipe 122, and Ln is the inlet pipe. 121 length (m).

  As shown in FIG. 1, the opening adjustment valve 11 is generally attached to the inlet pipe 121 of the Helmholtz resonance pipe 12. By adjusting the opening of the opening adjusting valve 11, the cross-sectional area An of the inlet pipe 121 can be changed, and the resonance frequency f of the Helmholtz resonance pipe 12 is variably adjusted from the equation (1). You can see that

  FIG. 2 is a characteristic diagram showing the resonance frequency in the cylindrical Helmholtz resonance tube 12 shown in FIG. 1, with the horizontal axis representing the length (Lr) of the resonance attenuation tube 122 and the vertical axis representing the resonance frequency (f). Yes. In this characteristic diagram, the diameter Dn of the inlet pipe 121 is used as a parameter. As can be seen from FIG. 2, the diameter Dn of the inlet pipe 121, the length Ln of the inlet pipe 121, the diameter Dr of the resonance damping pipe 122, the length Lr of the resonance damping pipe 122 (that is, the volume V of the resonance damping pipe 122), etc. Thus, the resonance frequency f of the Helmholtz resonance tube 12 is changed. For example, the resonance frequency f is changed by changing the diameter Dn of the inlet pipe 121. Therefore, by changing the opening degree of the opening adjustment valve 11 provided in the inlet pipe 121, the diameter Dn of the inlet pipe 121 can be changed equivalently, and the resonance frequency f of the Helmholtz resonance pipe 12 can be changed. Since the acoustic resonance mode sound wave length is usually longer than the pipe diameter, the resonance frequency f depends on the opening area of the inlet pipe 121 regardless of the shape of the opening. Therefore, the resonance frequency f of the Helmholtz resonance tube 12 can be adjusted regardless of the type of valve regardless of the type of the opening adjustment valve 11.

  The example shown in FIG. 2 shows three resonance frequency characteristics with respect to the length Lr of the resonance attenuating pipe 122 using the diameter Dn of the inlet pipe 121 as a parameter, and the resonance frequency f is reduced by narrowing the diameter Dn of the inlet pipe 121. Is low. That is, in one Helmholtz resonance pipe 12, if the opening degree of the opening adjustment valve 11 is changed, the diameter Dn of the inlet pipe 121 can be equivalently changed (that is, the sectional area An of the inlet pipe 121 is changed). This shows that the resonance frequency f of the Helmholtz resonance tube 12 can be variably adjusted.

  Further, as can be seen from the equation (1), even if the opening adjustment valve 11 is not provided in the inlet pipe 121, in other words, the diameter Dn of the inlet pipe 121 (that is, the sectional area An of the inlet pipe 121) is made constant. In addition, the resonance frequency f of the Helmholtz resonance tube 12 can be changed by changing the diameter Dr or the length Lr of the resonance attenuation tube 122 (that is, by changing the volume V of the resonance attenuation tube 122).

  Therefore, in the boiling water reactor of the present invention, the Helmholtz resonance tube 12 is attached to the side of the main steam system, and noncondensable gas such as hydrogen gas mixed in the steam passing through the main steam system is Helmholtz resonance. The Helmholtz resonance tube 12 is attached to the side of the main steam system by tilting the Helmholtz resonance tube 12 downwardly toward the main steam system so that no drain is accumulated in the Helmholtz resonance tube 12. The volume V of the resonance tube 12 is made constant. Therefore, the opening degree of the opening adjustment valve 11 is changed to adjust the diameter Dn of the inlet pipe 121, the resonance frequency f of the Helmholtz resonance pipe 12 is variably adjusted, and pressure vibration due to acoustic resonance generated in the main steam system is reduced. Suppressed. Hereinafter, some of the embodiments for effectively suppressing pressure vibration due to acoustic resonance generated in the main steam system by preventing the non-condensable gas and drain from staying in the Helmholtz resonance tube 12 will be described in detail.

<< First Embodiment >>
FIG. 3 is a configuration diagram showing a main steam system of the boiling water reactor according to the first embodiment of the present invention. In the lower part of the reactor pressure vessel 1, a reactor core or the like in which cooling water for generating steam 2 by uranium fission circulates is configured, but this is omitted in this figure. Steam 2 generated inside the reactor pressure vessel 1 flows into the steam dome 6 surrounded by the lid 5 of the reactor pressure vessel 1 after moisture is removed by the corrugated plate 4 inside the steam dryer 3. To do. Moisture removed by the corrugated plate 4 passes through the drain pipe 7 and is discharged below the steam dryer 3. On the other hand, the steam 2 flows from the nozzle 8 through the steam pipe 9 into the high-pressure turbine 10 and rotates a generator (not shown) at high speed.

  In addition, a Helmholtz resonance tube 12 having the configuration shown in FIG. That is, the Helmholtz resonance pipe 12 is installed with respect to the steam pipe 9 by communicating (venting) the opening on the side of the steam pipe 9 and the inlet pipe 121 of the Helmholtz resonance pipe 12. At this time, the Helmholtz resonance pipe 12 is inclined and installed on the side of the steam pipe 9 so that the inlet side of the Helmholtz resonance pipe 12 faces slightly below the side of the steam pipe 9. The installation method of the Helmholtz resonance tube 12 will be described in detail using an enlarged view.

  FIG. 4 is an enlarged view showing a state where the Helmholtz resonance tube 12 is installed on the side of the steam pipe 9 in the boiling water reactor shown in FIG. As shown in FIG. 4, the Helmholtz resonance pipe 12 is installed on the side of the steam pipe 9 by tilting the Helmholtz resonance pipe 12 so that the inlet pipe 121 attached to the side of the steam pipe 9 faces slightly downward. . That is, the Helmholtz resonance pipe 12 is inclined and installed on the side of the steam pipe 9 so that the drain generated in the Helmholtz resonance pipe 12 is continuously discharged to the steam pipe 9.

  By installing the Helmholtz resonance tube 12 on the side of the steam pipe 9 in this way, the non-condensable gas that passes only through the upper part of the steam pipe 9 transporting the steam 2 is absorbed by the resonance attenuation of the Helmholtz resonance pipe 12. There is no risk of stagnation by flowing into the tube 122. Therefore, the Helmholtz resonance tube 12 is always kept in an appropriate state. Further, the drain generated by a part of the steam transported by the steam pipe 9 staying in the resonance damping pipe 122 of the Helmholtz resonance pipe 12 is continuously discharged to the steam pipe 9 along the inclination of the resonance damping pipe 122. Therefore, there is no possibility that the spatial volume (volume) of the resonance attenuating tube 122 fluctuates due to drainage. As a result, the Helmholtz resonance pipe 12 can adjust the resonance frequency f only by the valve opening degree of the opening adjustment valve 11 provided in the inlet pipe 121 (that is, the sectional area An of the inlet pipe). By adjusting the degree adjusting valve 11, the amplitude of pressure vibration due to acoustic resonance generated in the steam pipe 9 can be effectively suppressed.

  A method for suppressing acoustic resonance realized by the Helmholtz resonance pipe 12 provided on the steam pipe 9 with an inclination as shown in FIG. 4 will be described in more detail. In the boiling water reactor of the first embodiment shown in FIG. 3, no pressure is applied to the space (main steam system) of the steam phase from the steam dome 6 to the high pressure turbine 10 through the nozzle 8 and the steam pipe 9. Sensors 13 and 14 are attached. Here, either one of the pressure sensors 13 and 14 may be used alone, or a plurality of each may be installed. The signal of the pressure vibration from the pressure sensors 13 and 14 is processed by a signal processing unit in the control device 15, and the opening degree of the opening degree adjusting valve 11 is controlled according to the magnitude of the pressure vibration amplitude.

  That is, the control device 15 inputs the pressure vibration signal of the pressure sensors 13 and 14 and optimally controls the opening degree of the opening adjustment valve 11 so that the amplitude of the pressure vibration of the pressure sensors 13 and 14 is minimized. To do. For example, when the opening degree adjusting valve 11 is slightly opened, if the pressure vibration amplitude of the pressure sensors 13 and 14 is reduced, the opening degree adjusting valve 11 is further opened minutely. Moreover, when the amplitude of the pressure vibration of the pressure sensors 13 and 14 increases, the opening adjustment valve 11 is controlled to be closed in the opposite direction. By repeating such an operation, the opening degree of the opening adjusting valve 11 is controlled (that is, the sectional area An of the inlet pipe 121 of the Helmholtz resonance pipe 12 is controlled), and the acoustic resonance of the steam pipe 9 is suppressed. To do. Thereby, the amplitude of the pressure vibration of the pressure sensors 13 and 14 can be minimized.

  FIG. 5 is a block diagram showing processing functions of the control device 15 suitable for use in the present embodiment. The control device 15 includes a signal processing unit 151 and a control unit 152. In the signal processing unit 151, the amplitude of the pressure vibration input from the pressure sensors 13 and 14 is stored in the storage unit 1511, and the pressure vibration amplitude of the pressure sensors 13 and 14 before and after the opening adjustment valve 11 is operated is compared with the comparison unit 1512. Compare with. Further, the control unit 152 determines a new opening command to the opening adjustment valve 11 based on the comparison result of the comparison unit 1512, and outputs a control signal to the opening adjustment valve 11.

  With such a function, the opening degree of the opening adjustment valve 11 of the inlet pipe 121 in the Helmholtz resonance pipe 12 is controlled in a direction in which the amplitude of the pressure oscillation of the main steam system decreases, and the inlet pipe 121 in the Helmholtz resonance pipe 12 is controlled. The substantial opening area (that is, the cross-sectional area An of the inlet pipe 121) is adjusted. Thereby, the resonance frequency f of the Helmholtz resonance tube 12 approaches the frequency of the resonance vibration generated in the main steam system, and the acoustic resonance (pressure vibration) of the main steam system can be attenuated.

  In the present embodiment, the Helmholtz resonance pipe 12 is installed at the side of the steam pipe 9 and the inlet pipe 121 of the Helmholtz resonance pipe 12 is provided at a position where the pressure oscillation amplitude is large in the main steam system, thereby acoustic resonance. The mode can be effectively attenuated. This embodiment is effective when the pressure vibration of the steam pipe 9 is large. For example, when a large pressure vibration occurs in the nozzle 8, the Helmholtz resonance pipe 12 is installed in the vicinity of the nozzle 8, thereby suppressing the pressure vibration of the steam pipe 9 and increasing the pressure vibration amplitude of the entire main steam system. Can be small. In particular, in the case of a boiling water reactor, since a safety valve is installed in the vicinity of the nozzle 8, when applying the configuration of this embodiment at the time of increased output, a large capacity with a large flow path area is large. By using a safety valve, it is possible to reduce the number of valves compared to before the increased output, and to install a Helmholtz resonance tube using a surplus valve seat.

  In addition to the fact that the non-condensable gas does not stagnate inside the resonance damping pipe 122 by attaching the Helmholtz resonance pipe 12 inclined to the steam pipe 9 side to the steam pipe 9 as in the present embodiment to the steam pipe 9, Since the drain accumulated in the resonance attenuating pipe 122 is always discharged to the steam pipe 9, the spatial volume (volume V) of the resonance attenuating pipe 122 is always kept constant. Therefore, by adjusting the opening degree of the opening adjustment valve 11 of the inlet pipe 121 by the control device 15 that performs control according to the signals from the pressure sensors 13 and 14, the cross-sectional area An of the inlet pipe 121 is set to an optimum value, Pressure vibration due to acoustic resonance of the steam pipe 9 can be effectively suppressed.

  That is, when the pressure wave propagates or reflects in the main steam system and is amplified, an acoustic resonance mode having a large amplitude is formed. When the pressure vibration at the inlet of the Helmholtz resonance tube 12 fluctuates in this acoustic resonance mode, the flow velocity toward the inside of the Helmholtz resonance tube 12 fluctuates. Therefore, when the opening degree of the opening adjustment valve 11 of the inlet pipe 121 is adjusted to maintain the sectional area An of the inlet pipe at an optimum value, the resonance frequency f of the Helmholtz resonance pipe 12 and the frequency of the acoustic resonance mode are matched. Since the flow velocity fluctuation at the inlet of the Helmholtz resonance tube 12 becomes large, the Helmholtz resonance tube 12 can absorb the acoustic energy in the main steam system, and can effectively attenuate the pressure vibration caused by the acoustic resonance mode. Therefore, the acoustic resonance mode can be effectively attenuated by providing the inlet of the Helmholtz resonance tube 12 at a position where the pressure oscillation is large in the main steam system. For example, when a large pressure vibration occurs in the vicinity of a valve (not shown) of the steam pipe 9, the pressure vibration is suppressed by installing a Helmholtz resonance pipe 12 at the position of the steam pipe 9 in the vicinity thereof, It is possible to reduce the pressure fluctuation applied to the steam pipe 9 and maintain a highly reliable operation.

<< Second Embodiment >>
FIG. 6 is a configuration diagram showing a main steam system of a boiling water reactor according to the second embodiment of the present invention. In the boiling water reactor according to the first embodiment shown in FIG. 3, the Helmholtz resonance tube 12 is installed inclined to the side surface of the steam pipe 9, but the boiling water reactor according to the second embodiment shown in FIG. Then, the Helmholtz resonance tube 12 is installed to be inclined to the side surface of the vapor dome 6. Since the other configuration is the same as that of the first embodiment shown in FIG. 3, redundant description will be omitted, and the configuration and operation unique to the second embodiment will be described.

  The mounting configuration of the Helmholtz resonance tube 12 to the steam dome 6 in the second embodiment shown in FIG. 6 will be described by replacing the steam pipe 9 in FIG. 4 with the steam dome 6. The Helmholtz resonance tube 12 having an inclination is installed in the steam dome 6. By installing the Helmholtz resonance tube 12 on the vapor dome 6 in such an inclined manner, non-condensable gas such as hydrogen gas existing on the upper portion of the vapor dome 6 does not stagnate in the Helmholtz resonance tube 12. Further, since the drain generated by the steam in the Helmholtz resonance tube 12 is discharged to the steam dome 6 along the inclination of the Helmholtz resonance tube 12, the drain does not stagnate in the Helmholtz resonance tube 12, and the Helmholtz resonance tube 12, the volume of the resonance attenuating tube 122 is kept constant.

  Therefore, for example, when the pressure sensor 13 detects the pressure vibration in the steam dome 6 and transmits the detection signal to the control device 15, the control device 15 processes the received pressure vibration signal to obtain the pressure vibration amplitude. The opening degree of the opening degree adjusting valve 11 is controlled according to the size. That is, the control device 15 inputs a pressure vibration signal from the pressure sensor 13 and optimally controls the opening degree of the opening adjustment valve 11 so that the amplitude of the pressure vibration of the pressure sensor 13 is minimized. For example, when the opening adjustment valve 11 is slightly opened, if the pressure vibration of the pressure sensor 13 decreases, the opening adjustment valve 11 is further opened slightly. Further, when the pressure vibration of the pressure sensor 13 increases, the opening adjustment valve 11 is controlled to close in the opposite direction. By repeating such an operation, the opening degree of the opening adjustment valve 11 is optimally controlled (that is, the sectional area An of the inlet pipe 121 of the Helmholtz resonance pipe 12 is optimally controlled), and the steam dome 6 is controlled. The amplitude of pressure vibration is attenuated by suppressing acoustic resonance.

<< Third Embodiment >>
FIG. 7 is a configuration diagram showing a main steam system of a boiling water reactor according to the third embodiment of the present invention. The description which overlaps with 1st Embodiment and 2nd Embodiment is abbreviate | omitted. A Helmholtz resonance pipe 12A is installed on the side of the steam pipe 9 through the opening adjustment valve 11A so as to incline with a downward slope toward the steam pipe 9 side, and the Helmholtz resonance pipe is provided through the opening adjustment valve 11B. 12B is installed to be inclined with a downward slope toward the steam pipe 9 side. The form in which these Helmholtz resonance pipes 12A and 12B are inclined and installed on the side of the steam pipe 9 is as shown in FIG. Therefore, the non-condensable gas passing through the upper part of the steam pipe 9 is not likely to stagnate inside the Helmholtz resonance tubes 12A and 12B, and the drain is not likely to stagnate.

  Accordingly, since the volumes of the Helmholtz resonance tubes 12A and 12B (that is, the volume of the resonance attenuation tube 122) are kept constant, the control device 15 causes the pressure vibration amplitude of the pressure vibration amplitude to be detected by the pressure signals detected by the pressure sensors 14A and 14B. By controlling the opening degree of the opening adjustment valves 11A and 11B according to the size, pressure vibration due to acoustic resonance generated inside the steam pipe 9 can be effectively suppressed.

  That is, in this embodiment, the steam header 16 is installed in the steam pipe 9. The steam header 16 is provided with a distributor-like role that enables equalization of each pipe of the steam pipe 9 constituted by a plurality of parallel pipes or branching to other pipes. Thus, when the steam header 16 is installed, the frequency phase of the acoustic resonance mode may be different before and after the steam header 16. Therefore, by providing the pressure sensors 14A and 14B and the Helmholtz resonance tubes 12A and 12B at the positions of the steam pipes 9 before and after the steam header 16, the acoustic resonance mode is effectively attenuated before and after the steam header 16. Can do.

  For example, when a large pressure vibration occurs before and after the steam header 16, the control device 15 controls the opening degree of the opening degree adjusting valves 11A and 11B based on the pressure signals detected by the pressure sensors 14A and 14B. By matching the resonance frequency of the Helmholtz resonance tubes 12A and 12B before and after the steam header 16 with the frequency of the acoustic resonance mode, the pressure vibration is suppressed in the entire area of the steam pipe 9, and as a result, the pressure vibration of the entire main steam system Can be suppressed.

  That is, the control device 15 inputs pressure vibration signals of the pressure sensors 13, 14A, 14B, and the opening degrees of the opening adjustment valves 11A, 11B are optimized so that the amplitudes of the pressure vibrations are minimized. To control. For example, when the opening adjustment valve 11A is slightly opened to reduce the pressure vibration of the pressure sensors 13, 14A, 14B, the opening adjustment valve 11A is further opened. Further, when the pressure vibration of the pressure sensors 13, 14A, 14B increases, the opening adjustment valve 11A is controlled to close in the opposite direction. By repeating such operations for the opening adjustment valves 11A and 11B, the opening degree of the opening adjustment valves 11A and 11B is controlled to minimize the amplitude of pressure vibration of the pressure sensors 13, 14A and 14B. Can do.

  The specific configuration of the control device 15 is the same as that in FIG. 5, but in the case of the third embodiment, the control unit 152 operates as follows. That is, the amplitude of pressure vibration from the pressure sensors 13, 14A, 14B is stored in the storage unit 1511, and the pressure vibration amplitudes of the pressure sensors 13, 14A, 14B before and after operating the opening adjustment valves 11A, 11B are compared. Part 1512 compares. And the opening degree of the opening degree adjustment valves 11A and 11B is determined from the comparison result, and the opening degree adjustment valves 11A and 11B are controlled.

  Also in the case of the boiling water reactor of the third embodiment shown in FIG. 7, if the inlet pipe 121 of the Helmholtz resonance pipes 12A and 12B is at a position where the pressure vibration of the steam pipe 9 is large, the acoustic resonance mode is more effective. Can be attenuated. Therefore, if the control device 15 is controlled using the pressure vibration signals from the pressure sensors 13, 14A, and 14B to determine the opening degrees of the opening adjustment valves 11A and 11B, the acoustics can be more effectively performed as follows. Resonance can be attenuated.

  That is, the acoustic vibration mode generated in the steam pipe 9 is calculated, and the opening degree adjustment valve 11A or 11B corresponding to the Helmholtz resonance pipe 12A or 12B provided at a position where the calculation result of the pressure vibration is large is sequentially opened. The degree is determined, and the control is sequentially performed from the opening adjustment valve. The acoustic vibration mode is obtained by numerical calculation using an appropriate boundary condition based on a compressible fluid equation or a sound wave equation as a basic equation, and pressure vibration at each position of the steam pipe 9 can be obtained. From this acoustic vibration mode, the amplitude of the pressure vibration at the position of the opening degree adjusting valves 11A and 11B is obtained, and the opening degree adjusting valve having the larger amplitude of the pressure vibration is preferentially controlled. By using such a method, it becomes possible to attenuate the pressure vibration by finding the optimum opening degree of the opening adjustment valves 11A and 11B in a shorter time.

<< Fourth Embodiment >>
FIG. 8 is a configuration diagram showing a main steam system of a boiling water reactor according to the fourth embodiment of the present invention. In this embodiment, one Helmholtz resonance pipe 12 is installed on the side of the steam pipe 9 via a plurality of opening adjustment valves 11 with a downward slope toward the steam pipe 9 side. The form in which the Helmholtz resonance pipe 12 having a plurality of opening adjustment valves 11 is installed at the side of the steam pipe 9 is inclined as shown in FIG. In other words, in FIG. 4, it can be read that a plurality of inlet pipes 121 and opening degree adjusting valves 11 are arranged in the back direction of the drawing and connected to the steam pipe 9 with respect to one resonance damping pipe 122. Good. With such an installation configuration, the non-condensable gas passing through the upper part of the steam pipe 9 is not likely to stagnate inside the Helmholtz resonance pipe 12, and the drain is not likely to stagnate.

  Further, pressure sensors 13 and 14 are attached to a space (main steam system) in the steam phase from the steam dome 6 to the high pressure turbine 10 through the nozzle 8 and the steam pipe 9. Here, either one of the pressure sensors 13 or 14 or a plurality of the pressure sensors 13 and 14 may be provided. The signal of the pressure vibration amplitude from the pressure sensors 13 and 14 is processed by a signal processing unit in the control device 15 to control the opening degree of the plurality of opening adjustment valves 11 according to the magnitude of the pressure vibration amplitude. used. Since the configuration of the control device 15 is the same as the configuration of FIG. 5 described in the first embodiment, a duplicate description is omitted.

  FIG. 9 is a schematic side view showing a Helmholtz resonance tube used in the present embodiment. In FIG. 9, for easy understanding, the steam pipe 9, the plurality of opening adjustment valves 11, and the Helmholtz resonance pipe 12 in the boiling water reactor shown in FIG. 8 are drawn together. . Each of the plurality of inlet pipes 121 connected to the side of the steam pipe 9 is provided with an opening degree adjusting valve 11, and these inlet pipes 121 are connected by a single resonance damping pipe 122. By setting the sum of the cross-sectional areas of the plurality of inlet pipes to An and the volume of the resonance attenuating pipe 122 to a constant value V, the resonance frequency f of the Helmholtz resonance pipe 12 can be obtained by the above equation (1). By controlling the cross-sectional area An and making the resonance frequency f coincide with the frequency of acoustic resonance of the steam pipe 9, pressure vibrations generated in the steam pipe 9 can be suppressed. In addition, by providing multiple opening adjustment valves in the Helmholtz resonance tube, the multiple opening adjustment valves are controlled in order according to the magnitude of the pressure vibration amplitude, so the pressure vibrations are suppressed finely. can do. The resonance attenuation pipe 122 is not limited to the pipe as shown in FIG. 9, and may be an annulus-like container arranged so as to surround the steam pipe 9.

  Further, by using the Helmholtz resonance tube 12 having the configuration as shown in FIG. 9, the Helmholtz resonance tube 12 can be compactly arranged along the steam pipe 9 even when there is no space around the steam pipe 9. Furthermore, since the Helmholtz resonance pipe 12 has a plurality of inlet pipes 121, the sum An of the cross-sectional areas of the inlet pipes 121 can be increased, so that the attenuation rate of the pressure vibration generated in the steam pipe 9 is increased. It becomes possible to do. For example, if the Helmholtz resonance tube 12 having a shape as shown in FIG. 9 is used at the time of increasing the output of the boiling water reactor, before the increase of the output by using a large-sized large-capacity safety valve having a large steam flow area. Since the number of valves can be reduced as compared with the above, means such as installing a Helmholtz resonance tube using a plurality of surplus valve seats are also possible.

<< Fifth Embodiment >>
FIG. 10 is a conceptual diagram showing an arrangement configuration of the Helmholtz resonance tube 12 applied to the fifth embodiment of the present invention. That is, in the boiling water reactors from the first embodiment to the fourth embodiment, the Helmholtz resonance pipe 12 is inclined downward toward the steam pipe 9 as shown in FIG. As a result, the non-condensable gas and drain were prevented from stagnating inside the Helmholtz resonance tube 12. In the fifth embodiment, as shown in FIG. 10, the Helmholtz resonance pipe 12 is installed on the upper part of the steam pipe 9, and the vent pipe 21 is connected to the steam pipe 9 from the upper part of the Helmholtz resonance pipe 12. The non-condensable gas and drain are prevented from stagnating inside the resonance tube 12.

  As shown in FIG. 10, if the Helmholtz resonance pipe 12 is installed on the upper part of the steam pipe 9 via the inlet pipe 121, there is no possibility that the drain is stagnated inside the resonance attenuation pipe 122. On the other hand, non-condensable gas such as hydrogen gas transported in the upper layer of the steam pipe 9 flows toward the resonance attenuation pipe 122, but these non-condensable gas passes through the vent pipe 21 to the steam pipe 9. Continuously discharged. According to such a configuration, the non-condensable gas does not stagnate inside the resonance attenuating tube 122, and the drain does not stagnate in the resonance attenuating tube 122. V) is always kept constant.

  For example, if the Helmholtz resonance tube 12 is installed in a boiling water reactor having the configuration shown in FIG. 3 in the arrangement as shown in FIG. 10, the spatial volume (volume V) of the resonance attenuation tube 122 is always kept constant. Therefore, the opening degree of the opening adjustment valve 11 disposed in the inlet pipe 121 is adjusted by the control device 15 that performs control according to the signals from the pressure sensors 13 and 14, and the sectional area An of the inlet pipe 121 is set to the optimum value. By doing so, pressure vibration due to acoustic resonance of the steam pipe 9 can be effectively suppressed. Of course, even if the Helmholtz resonance tube 12 is installed in the arrangement shown in FIG. 10 with respect to the boiling water reactor configured as shown in FIGS. 6, 7, and 8, the cross-sectional area An of the inlet pipe 121 is set to the optimum value. Thus, pressure vibration due to acoustic resonance of the steam pipe 9 can be effectively suppressed.

  By providing the vent pipe 21, a part of the steam 2 passing through the steam pipe 9 flows into the Helmholtz resonance pipe 12. Thereby, the flow in the coupling | bond part of the inlet piping 121 and the steam piping 9 changes. Since the magnitude of the pressure vibration suppression of the Helmholtz resonance pipe 12 varies depending on the flow fluctuation at the joint between the inlet pipe 121 and the steam pipe 9, the pressure vibration of the Helmholtz resonance pipe 12 is adjusted by adjusting the diameter of the vent pipe 21. It is possible to optimize the suppression effect.

<Summary>
In the boiling water reactors from the first embodiment to the fifth embodiment described above, the non-condensable gas such as hydrogen gas does not stagnate in the Helmholtz resonance tube 12, and therefore the boiling water reactor The Helmholtz resonance tube 12 can be maintained in a safe state during the operation. Further, since the drain does not stagnate in the resonance attenuating tube 122 of the Helmholtz resonance tube 12, the spatial volume (volume V) of the resonance attenuating tube 122 can always be kept constant. Therefore, by controlling the opening degree (cross-sectional area An) of the opening degree adjusting valve 11 attached to the inlet pipe 121, the resonance frequency f of the Helmholtz resonance pipe 12 is matched with the acoustic resonance frequency of the steam pipe. As a result, pressure vibration due to the acoustic resonance mode generated in the main steam system can be effectively suppressed.

  Further, in the boiling water reactors from the first embodiment to the fifth embodiment, the opening degree adjusting valves 11 are all attached to the inlet pipes 121 of the Helmholtz resonance pipe 12, and the controller 15 opens them. The degree of opening of the degree adjusting valve 11 is controlled. However, once the opening degree of the opening adjustment valve 11 is determined, thereafter, the opening degree of the opening adjustment valve 11 may be fixed and the control device 15 may be set to the non-control state, or the control device 15 may be removed. Also good. Further, once the opening degree of the opening degree adjusting valve 11 is determined, the opening degree adjusting valve 11 may be replaced with a piping element having a flow path area and length equivalent to the opening degree adjusting valve 11.

  Furthermore, in the boiling water reactors from the first embodiment to the fifth embodiment, the sound generated in the main steam system can be controlled only by controlling the opening of the opening adjustment valve of the inlet pipe in the Helmholtz resonance pipe. Since the amplitude of pressure vibration due to resonance can be minimized, it is possible to easily suppress pressure vibration without renewing the main steam system and Helmholtz resonance tube of the boiling water reactor. It becomes. Thereby, it is possible to construct a boiling water reactor capable of always maintaining the operation management of the power plant in the optimum state.

  Furthermore, since the drain does not stagnate in the Helmholtz resonance tube, the volume (internal volume) of the resonance attenuation tube can always be maintained at a constant value. Therefore, the amplitude of pressure vibration due to acoustic resonance generated in the main steam system can be minimized only by controlling the opening of the opening adjustment valve of the inlet pipe in the Helmholtz resonance pipe. In other words, pressure vibrations associated with acoustic resonances generated in the main steam system can be achieved simply by controlling the opening of the opening adjustment valve, without remodeling the main steam system or Helmholtz resonance tube of the boiling water reactor. It becomes possible to easily suppress the amplitude. Thus, the Helmholtz resonance tube can be maintained in an appropriate state during operation of the boiling water reactor.

  FIG. 11 is a characteristic diagram showing frequency versus sound pressure for explaining the effect of each embodiment according to the present invention, and shows typical test results with and without a Helmholtz resonance tube. The vertical axis in the figure represents the sound pressure on the surface of the steam dryer, and when there is no Helmholtz resonance tube, a pressure vibration peak occurs at a specific low frequency. The figure shows the case where the resonance frequency of the Helmholtz resonance tube is matched with the low-frequency pressure vibration peak, and it can be seen that the pressure vibration peak can be effectively attenuated by the Helmholtz resonance tube.

It is a side view which shows the structure of the cylindrical Helmholtz resonance tube suitable for using with the boiling water reactor of this invention. It is a characteristic view which shows the resonance frequency with respect to the dimension of the Helmholtz resonance tube shown in FIG. It is a block diagram which shows the main steam system of the boiling water reactor of 1st Embodiment in this invention. FIG. 4 is an enlarged view showing a state in which a Helmholtz resonance tube is installed on a side portion of a steam pipe in the boiling water reactor shown in FIG. 3. It is a block diagram which shows the processing function of the control apparatus used by each embodiment of this invention. It is a block diagram which shows the main steam system of the boiling water reactor of 2nd Embodiment in this invention. It is a block diagram which shows the main steam system of the boiling water reactor of 3rd Embodiment in this invention. It is a block diagram which shows the main steam system of the boiling water reactor of 4th Embodiment in this invention. It is a saddle-type side view which shows the Helmholtz resonance tube used in 4th Embodiment in this invention. It is a conceptual diagram which shows the arrangement configuration of the Helmholtz resonance tube applied to the 5th Embodiment of this invention. It is a characteristic view which shows the frequency versus sound pressure for demonstrating the effect of each embodiment in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reactor pressure vessel 2 Steam 3 Steam dryer 4 Corrugated plate 5 Reactor pressure vessel lid 6 Steam dome 7 Drain pipe 8 Nozzle 9 Steam piping 10 High-pressure turbine 11 Opening adjustment valve 12, 12A, 12B Helmholtz resonance pipe 121 Inlet piping 122 resonance attenuation pipes 13 and 14 pressure sensor 15 control device 151 signal processing section 1511 storage section 1512 comparison section 152 control section 16 steam header 21 vent pipe

Claims (5)

A reactor pressure vessel, a steam pipe for transporting steam generated inside the reactor pressure vessel to the outside from a steam dome above the reactor pressure vessel, and connected to the steam pipe and driven by the steam. In a boiling water reactor equipped with a high-pressure turbine
The steam pipe has a horizontal portion with a circular cross section, and a Helmholtz resonance tube is connected to the outer peripheral surface of the horizontal portion,
The Helmholtz resonance pipe includes a resonance attenuation pipe connected to the steam pipe via an inlet pipe, and a lower surface of the resonance attenuation pipe is inclined downward toward the steam pipe, and The boiling water nuclear reactor is connected to the outer peripheral surface of the steam pipe so that the inlet pipe is located below a horizontal center line of a cross section of the steam pipe . A reactor pressure vessel, a steam pipe having a circular horizontal section with a circular cross-section for transporting the steam generated inside the reactor pressure vessel from the steam dome above the reactor pressure vessel to the outside, and the steam In a boiling water reactor comprising a high-pressure turbine connected to piping and driven by the steam,
A damping resonance pipe connected to the outer peripheral surface of the steam pipe via an inlet pipe, the lower surface of the resonance damping pipe in the pipe is inclined downward toward the steam pipe, and the inlet pipe is A Helmholtz resonance tube connected to the outer peripheral surface of the horizontal portion of the steam pipe so as to be lower than the horizontal center line of the circular section of the steam pipe ;
A pressure sensor for detecting a pressure vibration amplitude caused by acoustic resonance generated when the vapor is transported;
A boiling water nuclear reactor comprising: an opening adjustment valve that adjusts an opening degree of an inlet pipe of the Helmholtz resonance pipe according to the magnitude of the pressure vibration amplitude detected by the pressure sensor. The Helmholtz resonance tube is arranged at a plurality of positions of the main steam system, in claim 2 in which the degree of opening of the inlet pipe of the Helmholtz resonance tubes disposed in a large position of the pressure oscillation amplitude, characterized in that it is adjusted The boiling water reactor described. The Helmholtz resonance tube has a plurality of opening adjustment valve, the opening regulating valve wherein the plurality of claim 2, characterized in that sequentially opening according to the size of the pressure oscillation amplitude is controlled Or the boiling water reactor of Claim 3 . A reactor pressure vessel, a steam pipe having a circular horizontal section with a circular cross-section for transporting the steam generated inside the reactor pressure vessel from the steam dome above the reactor pressure vessel to the outside, and the steam A high-pressure turbine connected to a pipe and driven by the steam, and a resonance damping pipe connected to the steam pipe via an inlet pipe, and a lower surface of the resonance damping pipe facing the steam pipe A Helmholtz resonance tube connected to the outer peripheral surface of the horizontal portion of the steam pipe so as to have a downward slope and so that the inlet pipe is below the horizontal center line of the circular section of the steam pipe. In the method for suppressing acoustic vibration of steam piping in a boiling water reactor equipped with,
Detecting a pressure vibration amplitude caused by acoustic resonance generated in a main steam system including the steam dome and the steam pipe;
Controlling the opening degree of the inlet pipe of the Helmholtz resonance pipe attached to the main steam system based on the detected pressure vibration amplitude;
And a step of fixing the opening of the inlet pipe when the magnitude of the pressure vibration amplitude is minimized. A method for suppressing acoustic vibration of a steam pipe in a boiling water reactor.

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